N-取代苯氨基乙酸的紫外光谱研究

本文测量了N~-取代苯氨基乙酸(RPhG,R=p-OCH_3,p-CH_3,m-CH_3,-H,m-OCH_3,p-Cl,m-Cl,m-NO_2,p-NO_2)在正己烷、正庚烷、二氧六环、四氯化碳、苯、甲苯、氯笨、乙酸乙酯、乙醇、乙腈、30％乙醇-水、不同比例的乙醇-正庚烧等溶剂中的紫外吸收光谱。实验结果显示:(1)与苯相比,RPhG在各溶剂中的紫外吸收峰均发生红移。(2)RPhG在各溶剂中的第一吸收谱带吸收频率ν与RPhG的碱性强度pK_2值、理论计算的电子跃迁能ΔE之间呈较好的直线关系。(3)在非极性溶剂中,RPhG的ν值与溶剂特性函数f(n~2)之间呈直线关系。在极性溶剂中,ν与溶剂特性函数f之间呈直线关系,[ν-(AL_0+B)f(n~2)]与溶剂特性函数φ-φ(n~2)之间也呈直线关系。(4)在不同溶剂中,同一取代基RPhG的ν~R对未取代PhG的ν~H之间存在着线性关系。     

N-取代苯基氨基乙酸乙酯的紫外光谱研究

本文用贝克曼DU-8B型分光光度计测量了N-取代苯基氨基乙酸乙酯(RPhGEt, R=p-OCH_3, p-CH_3, p-Cl, p-NO_2,-H, m-OCH_3, m-Cl, m-NO_2, m-CH_3)在水、二氧六圜。二氧六圜-水, 乙醇、乙酸乙酯、正庚烷、苯等溶剂中的紫外光谱。从实验结果发现, 在各溶剂中RPhGEt的紫外吸收频率, ~νI分别与偶极矩μ, 取代常数α’、碱性强度pK_2之间均存在着较好的直线关系。此外还研究了溶剂对~vI的影响, 得到RPhGEt的~νI值与溶剂的(n~2-1)/(n~2+2)之间有较好的直线关系。     

N-苯氨基乙酸与 N-α-萘氨基乙酸的离解常数

在25℃时及0.10M NaClO_4存在下,N-苯氨基乙酸((?)G)和 N-α-萘氨基乙酸(αNG)在30%(体积)乙醇中的表观离解常数用 pH 法测定为(?)G:pK_(COOH)=2.69,pK_(R_2NH_2)~+=4.72;αNG:pK_(COOH)=2.64,pK_(R_2NH_2)~+=10.83。为便于比较,氨基乙酸(G)的离解常数亦在相同情况下测定为 pK_(COOH)=2.71,pK_(R_2NH_2)~+=9.30。(?)G 和αNG 的硷性强度相差如此巨大,主要是由于后者有位阻效应之故。(?)G 的硷性比 G 的弱得多,因共轭效应起决定性的作用。改变溶剂的介电常数的结果是使氨基酸的酸硷性均减弱。     

N-环已烷氨基乙酸和N-β-萘氨基乙酸的离解常数

在25°及0.10M高氯酸鈉存在下,N-环己烷氨基乙酸(CyG)和N-β-萘氨基乙酸 (βNG)在30％(体积)乙醇中的表观离解常数用pH法測定为:CyG:pK_(COOH)=2.70,pK_(R_2NH_2~+)=9.83;βNG:pK_(COOH)=2.26,pX_(R_2NH_2~+)=4.46。前者(CyG)的酸碱強度均与氨基乙酸(G)的相似,但后者(βNG)的碱性却小于其异构体N-α-萘氨基乙酸(αNG)的碱性約百万倍,而与N-苯氨基乙酸(φG)的碱性相似。这进一步說明αNG上的8位氫原子和1位上羧甲氨基之間的空間效应是导致其碱性增強的主要原因。βNG的酸性較αNG略強,可能是在共軛程度較高的βNG分子中,N的电子密度較低的β-萘氨基对于羧基所产生較大的誘导效应之結果。     

N-(对-取代苯基)氨基乙酸的离解常数

前曾报导了氨基乙酸氮原子上的氢被不同烷基、环烷基和芳基等取代后的酸碱强度的改变情况^[1,2].苯环取代后,由于氮原子上孤对电子和苯环π电子产生共轭效应,因而导致亚胺基的碱性大为降低.     

N-(间-取代苯基)氨基乙酸的离解常数

本文研究了N-苯基氨基乙酸中苯环间位不同取代基对氨基酸酸碱强度的影响。将按前文方法制得的N-(间-取代苯基)氨基乙酸乙酯用氢氧化钠水溶液皂化,然后用浓盐酸酸化即得N-间-取代苯基氨基乙酸。在0.1M NaClO_4存在下,于15±0.2,25±0.2,35±0.2℃,用配有231型玻璃电极和甘汞电极的PHS-2型酸度计测定了N-(间-取代苯基)氨基乙酸在30%(体积)乙醇中的离解常数。用氨基酸钠盐测定离解常数的方法业已报道。从所测得的氨基酸表观离解常数(表1)可以看出,如同N-(对-取代苯基)氨基乙酸一样,N-(间-硝基苯基)氨基乙酸(m-NO_2PhG)的pK_1值反而比N-(间-氯苯基)氨基乙酸(m-ClPhG)和N-(间-甲氧苯基)氨基乙酸(m-CH_3OPhG)的大。这是不能用诱导效应来解释的。一般说来,氨基酸具有两性离解的性质,存在下列平衡:     

二苯并富烯紫外光谱的取代基效应

通过芴和芳香醛在相转移催化剂三乙基苄基氯化铵存在下发生缩合反应,合成了12个标题化合物, 测定了前7个化合物在17种溶剂中的紫外光谱, 在极性和非极性溶剂中, 其紫外光谱的最大吸收峰频率与Hammett亲电取代常数之间呈良好的线性关系。     

N-苯氨基乙酸和N-α-萘氨基乙酸与钴(Ⅱ)、镍(Ⅱ)络合物的结构研究

制备了 N-苯氨基乙酸(φG)和 N-α-荼氨基乙酸(αNG)与钴(Ⅱ)、镍(Ⅱ)的络合物,经磁化率、热谱、红外和光声光谱的测试,确定水合络合物结构为畸变八面体型、螫合环在 xy 平面上,z 轴上有两个水分子参与配位;无水络合物也是六配位的,N-取代氨基乙酸成为三啮配体,羰基氧参与配位并发生桥联.     

N-苯氨基乙酸和 N-α-萘氨基乙酸与铜(Ⅱ)和镍(Ⅱ)络合物的稳定性

N-苯氨基乙酸和 N-萘氨基乙酸与铜(Ⅱ)和镍(Ⅱ)在25℃时生成络合物的逐级生成常数曾用电势滴定法予以测定。实验在30%(体积)乙醇溶液中及有0.10M 高氯酸钠存在下进行。为便于比较,也在相同条件下测定氨基乙酸与铜和镍的络合物。N-苯氨基乙酸络合物的稳定性最小,由于络合剂的硷性太弱之故。实验结果表明镍的络合物具四面体结构,N-萘氨基乙酸镍的顺磁性亦证明此点。铜(Ⅱ)与氨基乙酸和 N-苯氨基乙酸的络合物为平面型结构(dsp~2,共价键),但 N-萘氨基乙酸铜却因位阻效应而改变其平面型结构,可能为四面体或变形的 dsp~2型结构。在30%乙醇溶液中,由于溶剂的介电常数降低,络合物的稳定性增强。     

N-(取代苯氨基硫代甲酰基)邻苯二甲酰胺酸的合成

本文用四种硫脲衍生物和一种脲衍生物同邻苯二甲酸杆进行单酰化反应, 筛选了最适宜反应条件, 避免了环状副产物, 合成了N-(取代萃氨基硫代甲酰基)邻苯二甲酸。     

对苯二胺和N-取代衍生物正离子自由基的共振喇曼光谱研究

本文中报道了对苯二胺和四种N-烷基取代衍生物正离子自由基的共振喇曼光谱, 揭示了自由基是具有明显C=C和C=N双键性质的半醌式结构, N原子上给电子基团的取代引起上述化学键振动峰低频移动, 反映出结构一端N上有烷基的自由基中与取代基直接相连的N原子失去一个p电子带正电荷, 并吸引环上的π电子形成一定程度C=N双键. 共振喇曼光谱随激发光波长的变化表明, 自由基的两个可见电子吸收带分别主要产生于环结构的π→π*和包含N原子结构的n→π*电子跃迁。     

PHOTOELECTRON AND ULTRAVIOLET ABSORPTION SPECTRA OF THE ENAMINES OF A SERIES OF SIMPLE POLYENES

Abstract— The photoelectron and ultraviolet absorption spectra of a series of enamines containing one, two or three double bonds have been determined. In all cases. the ionízation potential and lowest frequency absorption bands are at considerably lower energies than for the corresponding imines (Schiff bases). It is suggested that these facts should be taken into account when the structures of the various intermediates in the cycles of rhodopsin and bacteriorhodopsin are assessed.     

ULTRAVIOLET ACTION SPECTRA FOR AEROBIC AND ANAEROBIC INACTIVATION OF Escherichia coli STRAINS SPECIFICALLY SENSITIVE AND RESISTANT TO NEAR ULTRAVIOLET RADIATIONS

Abstract— Action spectra for the lethal effects of ultraviolet light (254–434 nm) irradiation delivered under aerobic or anaerobic conditions to Escherichia coli RT2 (specifically sensitive to near-UV radiation; > 320 nm) and E. coli RT4 (near-UV resistant) were prepared. Negligible oxygen dependence was observed for both strains below about 315 nm. The oxygen enhancement ratio (OER) for RT4 increased above this wavelength to the longest wavelength used, whereas for RT2 there was a greater increase in the OER to a large peak at 365 nm, then a progressive decrease at longer wavelengths. The results are consistent with the possibility that the sensitivity of strain RT2 to near-UV radiation may be due to hyperproduction of photosensitizer, operating via photodynamic type reactions involving excited species of oxygen.     

N-(4-羟基苯基)马来酰亚胺的合成及其光谱分析

利用对氨基酚和马来酸酐反应制取N-(4-羟基苯基)马来酰亚胺(HPM),并采用红外光谱及核磁光谱对其结构进行了表征.研究了HPM在甲醇、四氢呋喃及二氯甲烷3种溶剂中的紫外光谱.结果发现,在这3种溶剂中,HPM在210～250 nm范围内的吸收峰对溶剂极性及溶液浓度敏感;而275 nm左右的吸收峰在各种极性不同溶剂中位置...     

ULTRAVIOLET ACTION SPECTRA (280 to 380 nm) AND SOLAR EFFECTIVENESS SPECTRA FOR HIGHER PLANTS

Several ultraviolet (UV) action spectra that typify the responses of higher plants to irradiation by wavelengths between 280 nm and 380 nm are shown. An attempt is made to generate common spectra that may be used, at least temporarily, to represent the effects of UV on such important biological parameters as photosynthesis. The goal is to provide an estimate of plant response to solar UV and to the potential increase in ground level UV postulated for a depleted stratospheric ozone layer. Solar plant damage effectiveness curves are generated under "normal" solar UV conditions, and under an assumed UV increase corresponding to a 16% depletion in total ozone. Additional effects due to ozone depletion are concentrated in the UV-B region, especially at wavelengths between about 297 nm and 315 nm. Common features of these effectiveness curves are noted, and limitations are pointed out. As expected, no common spectrum has been found that can substitute for any specific spectrum nor that is unique enough to provide more than a limited first approximation of a plant damage spectrum. Additional information must be generated to fulfill this need.     

REVISED SPECTRA FOR THE INACTIVATION OF HAEMOPHILUS INFLUENZAE TRANSFORMING DNA BY MONOCHROMATIC ULTRAVIOLET LIGHT: EFFECT OF HISTIDINE

Abstract—It was reported previously that histidine sensitizes the genetic activity of Haemophilus influenzae transforming DNA to pure 334 nm ultraviolet light, Further measurements show that this apparent 334 nm sensitization was probably erroneous and that in fact, histidine protects DNA against inactivation by 334 nm light. This is now consistent with all previous observations that transforming DNA is protected by histidine against all near-UV wavelengths (above 320 nm) investigated.
A modified spectrum for the protection of H. influenza transforming DNA by histidine against ultraviolet light is described.